Collaborative Research: Most Arctic Plants Obtain Nitrogen by Symbiosis with Fungi: Development of a Radical Concept Cooperative Project

合作研究：大多数北极植物通过与真菌共生获取氮：开发激进概念合作项目

• 批准号: 0612595
• 负责人: John Hobbie
• 金额: $ 12.03万
• 依托单位: Marine Biological Laboratory
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-15 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0612595&HistoricalAwards=false
• 关键词: Collaborative; Research; Most; Arctic; Plants

P.I.: John Hobbie Proposal Number: 0612595P.I.: Erik Hobbie Proposal Number: 0612598Arctic plants are strongly limited by low levels of available nitrogen (N) yet organic N in the soil is abundant. To aid in obtaining nitrogen and other nutrients, woody plants form symbioses with mycorrhizal fungi. In this symbiosis, fungi obtain inorganic and organic N from soil N pools and transfer organic N compounds to plants while obtaining sugars from plants. Research into these pathways until now was either qualitative or relied on added isotopic N-organic compounds at artificially high concentrations, making extrapolation to natural ecosystems difficult. Now, new research in tussock tundra at Toolik Lake, Alaska uses natural levels of isotopic N to quantify the amount of N supplied to plants by the symbiosis as well as the amount of carbon moving from the plants to fungi. A second new method determines directly the presence of soil-derived organic N in plant and fungal tissues by natural radiocarbon measurements on protein vs. structural C. Implications for Arctic research on C and N cycling include the following: 1) to understand current N cycling and predict N cycling under future climates, information is needed on what controls mycorrhizal growth and whether these fungi can access nitrogen locked in soil organic matter; 2) models of pan-Arctic carbon cycling must be modified to include the energy cost to plants of mycorrhizal growth and the accompanying supply of nitrogen to woody plants by mycorrhizal fungi. Broader impacts resulting from the proposed activity include training of graduate and undergraduate students. K-12 students at Barrow (predominately Inupiat Eskimo) will learn about the project and assist in collecting mushrooms and plants through the Barrow Schoolyard program, funded in part by the Arctic LTER project. This research project will set up a partnership between an undergraduate institution and two research institutions. The research findings may create a paradigm shift -- forest and ecosystem scientists must now take into consideration the mycorrhizal symbionts and their role in supplying organic nitrogen from soil to shrubs and trees. Research emphasis will refocus to study the fungal abilities to attack soil organic matter. New measurements must be made of the effects of increased CO2 concentrations and a warming climate on below-ground N cycling and allocation to fungal symbionts. Because this study will provide methods to assess the importance of both C allocation to mycorrhizal fungi and organic N uptake in ecosystems, it will facilitate the inclusion of these important processes in ecosystem C and N models used for management.

P.I。：John Hobbie提案编号：0612595P.I。：Erik Hobbie提案编号：0612598 artctic植物受到低水平的可用氮（N）的强烈限制，但土壤中的有机N含量丰富。为了帮助获得氮和其他营养，木本植物与菌根真菌形成共生。在这种共生中，真菌从土壤n池中获得无机和有机n，并将有机N化合物转移到植物中，同时从植物中获取糖。到目前为止，对这些途径的研究要么是定性的，要么依赖于人为高浓度的同位素N-有机化合物的添加，从而使对天然生态系统的推断变得困难。现在，阿拉斯加工具湖的Tussock Tundra的新研究使用自然水平的同位素N来量化共生的N含量以及从植物到真菌的碳量以及碳的数量。 A second new method determines directly the presence of soil-derived organic N in plant and fungal tissues by natural radiocarbon measurements on protein vs. structural C. Implications for Arctic research on C and N cycling include the following: 1) to understand current N cycling and predict N cycling under future climates, information is needed on what controls mycorrhizal growth and whether these fungi can access nitrogen locked in soil organic matter; 2）必须修改泛氧化碳循环的模型，以包括菌根生长的植物的能源成本，以及菌根真菌向木质植物供应氮的能源成本。拟议的活动造成的更广泛的影响包括对研究生和本科生的培训。 Barrow的K-12学生（主要是Inupiat Eskimo）将了解该项目，并通过Barrow Schoolhard计划协助收集蘑菇和植物，该计划部分由北极lter项目资助。该研究项目将在本科机构和两个研究机构之间建立合作伙伴关系。研究发现可能会引起范式转移 - 森林和生态系统科学家现在必须考虑到菌根的共生体及其在向灌木和树木提供有机氮中的作用。研究重点将重新研究研究真菌能力以攻击土壤有机物。必须对增加二氧化碳浓度的影响和温暖气候对地下N循环和对真菌共生体的分配的影响进行新的测量。因为这项研究将提供评估生态系统中C分配对菌根真菌和有机N摄取的重要性的方法，因此它将促进将这些重要过程纳入用于管理的生态系统C和N模型中。